1. Field of the Invention
The present invention relates to a method of mounting an electronic component by connecting an electronic component to a printed circuit board using isotropic conductive adhesive, and a method of mounting an electronic component by connecting an electronic component to a printed circuit board using anisotropic conductive adhesive.
2. Description of the Related Art
A conventional method of connecting an electronic component to a printed circuit board is a reflow mounting method using solder paste, in which leads of the electronic component and electrodes on the printed circuit board are connected in such a manner that solder paste is printed on the electrodes on the printed circuit board through a metal mask, then the electronic component is placed on the printed circuit board, and the solder paste on the electrodes is heated and melted in a reflow furnace.
Recently, however, it has been pointed out that the lead component contained in solder paste in the above mentioned method of mounting an electronic component using solder paste causes negative influences on the human body and the global environment.
As a measure to prevent the various negative influences by the lead component of the solder paste, a method of connecting an electronic component on a printed circuit board has been provided using isotropic conductive adhesive comprising a resin-based binder mixed with filler in place of the solder paste.
In this method using isotropic conductive adhesive containing a resin-based binder, a printed circuit board and an electronic component can be connected through the same steps as in the reflow mounting method using solder paste.
However, this mounting method using isotropic conductive adhesive requires the printing of the isotropic conductive adhesive on the printed circuit board via a metal mask, manufacturing the metal mask and printing step are indispensable. Therefore, no improvement has been made by this method in connection with the complicated mounting step of an electronic component and the complexity of working facilities.
Further, since this mounting method using isotropic conductive adhesive requires the printing of the isotropic conductive adhesive on the printed circuit board via a metal mask, the distance between adjacent printing areas cannot be too small, and also it is difficult to connect to so called "high-density fine-pitch an electronic component having the lead pitch of 0.3 mm or less, for example.
Accordingly, it is an object of the present invention to provide a method of mounting an electronic component on a printed circuit board using an isotropic conductive adhesive, whereby the negative influence of the lead component in the adhesive on the human body and the global environment is prevented, and a high-density fine-pitch electronic component can be connected on the printed circuit board without requiring complicated steps and complex equipment.
Meanwhile, as another measure to prevent various negative influences of the lead component contained in solder paste in the method of mounting an electronic component using solder paste, a method of connecting an electronic component on a printed circuit board using anisotropic conductive adhesive comprising a resin-based binder mixed with filler in place of the solder paste, has been provided.
As is widely known, the anisotropic conductive adhesive can maintain insulation between adjacent electrodes. Therefore, a high-density fine-pitch component for which the lead pitch is 0.3 mm or less, for example, can be connected on a printed circuit board if the anisotropic conductive adhesive is used.
It is also widely known that when the connection between the components and the printed circuit board is made using anisotropic conductive adhesive, a heating step and a pressurizing step by thermo-compression bonding equipment are indispensable after supplying anisotropic conductive adhesive between the electronic component and the printed circuit board.
In other words, in the method of connecting a printed circuit board and an electronic component using anisotropic conductive adhesive, the negative influence caused by the lead component can be prevented and a high-density fine-pitch electronic component can be connected to the printed circuit board. However, since the heating step and the pressurizing step are required, there arise such problems that the connecting step will be complicated and the equipment used for the connection step will be complex.
Accordingly, it is another object of the present invention to provide a method of mounting an electronic component on a printed circuit board using anisotropic conductive adhesive, whereby the negative influence of the lead component on the human body and the global environment is prevented, and a high-density fine-pitch electronic component can be connected on the printed circuit board without requiring complicated steps and complex equipment.